The present invention relates to a portable circuit tester. In recent years there has been a virtual explosion in the market for integrated circuit electronics, both analog and digital. In many applications where high precision and a tolerance of extreme environmental conditions are required, hybrid integrated circuits are also popular.
Today there are hundreds of standard integrated circuits available all of which fit in one of several standard socket configurations. The most widely known configuration being a standard dual-in-line (DIP) socket for circuits having between four and sixteen pins. More recently twenty-four pin and forty pin dual-in-line configurations having wider spacing between the rows of sockets have become popular in the field of large scale integrated circuits (LSI).
It is been desirable to have an automatic testing apparatus for circuitry provided by a manufacturer as a quality control tool.
As greater and greater circuit density has been obtained in the field of integrated circuits, together with the ability to fabricate circuits on relatively large chips, the field of large scale integrated circuits has provided extremely complex functions available in standard integrated circuit (IC) packages. Many modern integrated circuits contain such complex functions that it is impractical to manually manipulate equipment to sequentially test various inputs and outputs in order to ascertain whether the circuit is operating properly. This increases the need for automated equipment which can take advantage of the inherent speed associated with the integrated circuit and perform a test of all possible inputs in a short period of time.
The proliferation of the use of integrated circuits in consumer products has created a need for a portable testing device for complex integrated circuits. It is becoming more and more difficult for maintenance personnel to ascertain when a particular integrated circuit in a device has failed. This is particularly true in apparatus where an integrated circuit may fail during a particular step of a sequential set of functions but the failure will not be apparent during steady state conditions under which the maintenance personnel may be performing tests.
Examples of previous automatic test equipment which includes programmable test routines are shown in U.S. Pat. No. 3,764,995 to Helf et al.; U.S. Pat. No. 3,622,876 to Ure et al.; and U.S. Pat. No. 4,053,844 to Hamaoui.
A portable programmed circuit tester is shown in U.S. Pat. No. 4,108,358 to Niemaszyk et al. This device includes a central processing unit and a program for executing a plurality of tests for different circuits.
A disadvantage of devices such as those shown in the Niemaszyk et al. patent is that such a device is large and impractical for use in field maintenance work.
Heretofore it has not been known in the art how to miniaturize a device such as that shown in the Niemaszyk et al. patent and to make same operate from a storage battery in a practical manner which allows use of the device in the field.